Attractive Forces

m1,m2: mass of two objects; r: distance between two objects; G: gravitational constant

Gravitational Force

M: Earth mass, m: mass of object, R: Earth radius, h: object’s height

Gravitational Acceleration

At a height h above the normal surface of the earth

Near the sea level

Force Of Gravity

Force of gravity on earth, a special case of Gravitational force

Newton's First Law

F: forces acting on the object , v: velocity of the object, a: acceleration of the object

Newton's Second Law

m: object’s mass(kg)

Newton's Third Law

Linear Elasticity-Hooke's Law

K: spring constant (n/m), x: displacement(m)

A Mass suspended by a spring

Force Of friction

µ: coefficient of friction, N: normal force

            Fms = µN
                = µPcosα
                = µmgcosα